31
Operation
7
Operation
Precautions
WARNING
The broadcast industry has recently recognized the potential medical
hazards of intense radio frequency radiation. Don't expose personnel to
personal harm. For reference, see CFR 29, Section 1910.97, the OSHA
standard for exposure to non-ionizing radiation. Whenever a rigger is on
the tower in the area of the antenna, shut off the transmitter and lock it
off so that it cannot be turned on accidentally.
CAUTION
Never operate the antenna system without proper purging and constant
positive dry gas pressure. Shively Labs will not accept responsibility for
antenna failure after operation without proper purging or positive pres-
sure of dry air or dry nitrogen.
CAUTION
Don't leave the de-icer on for extended periods when the weather is
above 60° F (16° C); it may overheat and be damaged.
The Antenna
Once the antenna has been installed and tested according to this manual, sim-
ply apply the transmitter signal. Don't exceed the rated power capacity of the
antenna.
To obtain the best performance and dependability from your Shively Labs
antenna, read and follow the "maintenance" section of this manual.
The De-Icer System
There is a generous margin of safety built into the de-icer system, and opera-
tion for prolonged periods below 60° F (16° C) will do no harm. If icing condi-
tions are expected, the heaters should be turned on ahead of time as a
preventive measure. It is much easier to prevent ice formation than to remove
a heavy coating. Thermostatic control systems which sense temperature con-
ducive to ice formation are highly desirable and are available from Shively
Labs upon request.
If you have the Shively Labs de-icer control box, you have the choice of man-
ual or automatic operation. There are three switch settings: AUTOMATIC, OFF,
and MANUAL. When the switch is set to AUTOMATIC, the thermostat turns the
heaters on and off according to the temperature. When the switch is set to
OFF, the thermostat is overridden and the heaters will stay off no matter what
the temperature.
When the switch is set to MANUAL, the thermostat is overridden and the heat-
ers will stay on no matter what the temperature.
The rate of ice removal will vary greatly with temperature, wind speed, and
type of ice. As a guide, the de-icers will remove
1/4 inch (6 mm) of clear ice at 32° F (0° C) in still air in about 15 minutes.
